Contributing Factor Map: A Taxonomy of Influences on Human Performance and Health in Space

The ability of crewmembers to perform critical functions during spacecraft operations is widely recognized as essential to mission success. This necessity motivates the characterization of factors influencing crewmember performance so that those with positive effects can be enhanced, and those with negative impacts can be minimized. Risk analysis techniques support such characterization, and whether qualitative or quantitative, they require a model of the system of interest. In human reliability analysis (HRA) applications, performance-shaping factors (PSFs) represent the model of the environment influencing human performance within a given scenario. Sets of PSFs in existing HRA methods are terrestrially based and, therefore, do not address additional factors relevant to spaceflight. This paper focuses on the development of a taxonomy, or qualitative model, of factors specific to spaceflight. The development as influenced by software and system modeling concepts and data availability constraints is discussed. A visual representation of the taxonomy, the contributing factor map (CFM), is also presented. We discuss current benefits resulting from the two contributions of the taxonomy and CFM. These include the existence of a set of PSFs specific to spaceflight, a framework for relating data at various levels of abstraction, and the CFM as a visual communication tool supporting horizontal and vertical integration across disciplines and throughout organizational structures. This paper includes an example application based on the risk of bone fracture in spaceflight. It also suggests follow-on applications of the CFM as a quantitative model framework and a “menu” of factors to consider in risk analysis and management activities.